1. Field of the Invention
For aircraft fuselages, horizontal stabilisers, etc.
2. Description of the Related Art
Existing aerodynamic profiles have a transversal cross-section with a rounded leading edge which is partly elliptical or oval, with the trailing edge ending in a very acute dihedral angle, the upper surface being convex and the lower surface substantially flat, and with a relatively high lift/resistance ratio.
The enhanced aerodynamic profile of the invention consists of a profile which is similar to that in U.S. Pat. No. 9,701,753, applied to fuselages and consisting of three sections: a front or leading edge of two sides or plates forming an acute dihedral angle with the vertex facing forward, a central section formed by two parallel sides or plates, and a rear section or trailing edge formed by two sides or plates at an acute dihedral angle with the vertex facing rearward. This profile ensures maximum performance, namely a maximum lift/resistance ratio per unit of surface. The unions on the lower or upper surfaces are suitably rounded. The sides or plates of the profile of the three sections may be flat, curved, semi-cylindrical or semi-conical.
The top of the leading-edge is an extension of the top of the flat central section, and the lower inclined surface of the front area is a ramp beginning in the top front area and dropping in a rearward incline to the bottom fact of the central section. The bottom of the trailing egde is an extension to the bottom of the central section, the upper face of which slopes from the trailing edge and is a ramp begining at the top of the central section, dropping in a rearward incline until meeting the base. Here, lift is produced in the front and rear section of the profile.
In one variant, the central section of the profile is slightly inclined with the bottom of the leading edge extending with the bottom of the central section and the horizontal top, said top having its trailing edge in an extension with the top of the central section and the lower horizontal part. Here, lift occurs over the whole profile
In all cases, the aerodynamic profile may be slightly curved, with convexity toward the upper surface.
A third variant has a horizontal leading edge and curved central section and trailing edge, forming an arch with the convexity toward the extrados. This provides lift over the centre and rear of the profile.
These profiles are correct for horizontal flight with limited leading angle.
To be practical for certain leading angles and prevent loss of the boundary layer and air current on the extrados, the following front section or rotary or fixed leading edge must be employed.
a) The front section is a fin or cone turning on an axis which divides it into two unequal parts, the rear part being larger. Said fin or cone has the lower surface of its rear section inclined, adapting with another which is inclined in the upper front part of the central section. Said fin with positive leading angles is automatically oriented with the direction of the ram air, to form a groove or slot between said section and the front of the central section whose leading edge cuts the air with a very acute dihedral angle, with its upper face approximately parallel to the ram air, while a spring tends to keep the fin and main body together. An anti-gust ram prevents rapid movements of the fin or cone. This can also be done with a small rotary fin or cone in the upper part of the front section.
b) In a variant, the fin or cone is turned on its axis by a hydraulic ram or electric system, etc.
c) A further variant has the top of the front area curved slightly downward and grooves or slots between the intrados and extrados to reduce or delay the release of the boundary layer and air current on the extrados. These grooves or slots are optional.
d) Also can be used an small rotary fin or cone on the upper part of the front section, said fin is actuated by a ram.
e) The upper, front and rotating sharp edge or cone, with the lower surface flexible or divided by two springs or steel tapes, and the upper surface sliding and slightly close to the upper surface of the extrados.
f) in another variant, the profile uses a very thin and slightly inclined profile with its trailing edge in the same direction that the ram air, with a front flexible zone and a fin that rotates around a very forward shaft, that allows the fin orientates with all leading angles, and the rear zone of the profile is fixed an rigid.
Operation
As the aircraft and the profile move forward, the air arriving for example at the area of the arrow 6 is forced to descend to the level of the area of the arrow 7, producing a reaction that tends to raise the aerodynamic profile.
Another interpretation could be that the air reaching the inlined frontal area and/or the central zone and/or the rear zone deflects the air downward, thus creating an upward reaction of the profile, in other cases, on leaving the inclined lower zone, there is also an upward reaction.
For positive leading angles, the frontal rotary fin or cone is oriented by the ram air, further creating a groove or slot preventing the release of the lower surface air current.